The present invention generally relates to devices and systems for providing protective control to power networks. More particularly, the present invention relates to the remote control of protective relays and remote display of power system data.
Protective relaying devices are widely known and used for providing protective control of power systems. Such protective relays incorporate a digital microprocessor for providing protective control of power distribution systems. There are known digital protective relays which have communications capabilities. A microprocessor-based protective relaying device having communications capability is disclosed, for example, in U.S. Pat. No. 5,982,585. However, the communications capabilities are typically relatively limited, and might include, for example, an application layer protocol such as Modbus RTU or ASCII for communication over a Universal Asynchronous Receiver Transmitter (UART) data link layer with an RS485, RS232 or other fiber optic physical layer interface. Typically, digital protective relays having a communications capability support only one application layer communications protocol, even where the relay includes multiple communications ports.
U.S. Pat. No. 5,680,324 discloses a communications processor for electric power substations. The communications processor includes an electronic network system with seventeen individual communications ports, four quadrature UART devices, each of which serves four of the ports, and a microprocessor which processes and controls the flow of data under the control of stored control programs, command settings, and command logic. Relays, meters, or other intelligent electronic devices are connected to some of the ports, and remote terminal units, local computers, or a modem are connected to master ports. The communication processor has a capability of communicating with the various port devices through an ASCII communication format. The processor is capable of supporting simultaneous communication with multiple devices and users. However, the processor is a centralized communication device, which is separate and distinct from the protective relays, meters, and other port devices. Accordingly, the >324 patent does not focus on the communications capabilities of the relays or other port devices.
Digital protective relays incorporating communications capabilities require a human machine interface (HMI) which allows a user to perform configuration and control tasks, and which retrieves and displays to the user information stored within the relay. Conventionally, the HMI interface is implemented in product-specific software, and manufacturers of relays may have more than a dozen different HMI software packages to communicate with various types of relays.
To further enhance the utility of a digital protective relay, and to provide more comprehensive protective control of power distribution systems, it would be desirable to improve the communications capabilities of digital protective relays. More particularly, it would be desirable for a protective relay to include a Human Machine Interface which incorporates a common “off-the-shelf” software package which is not product-specific. Known protective relays do not sufficiently address these needs.